Japanese Baseball Before 1945

by Jim Albright

Even a casual look at NPB baseball records clearly shows that from the founding of NPB
through 1944 was a pitcher dominated era. When I was trying to evaluate the major league
capabilities of NPB stars who played in this time frame, I had to measure the size of this
effect as best I could. I used the matched at bats method I've used several times in the
past, and came up with 155 players who batted at least once before 1945 and at least once
after 1945. They had a total of 61,461 matched at bats. The comparison is as follows:

AB

H

2B

3B

HR

BB

SO

AVG

OBP

SLG

Before

61,461

13,574

1834

582

287

8362

5893

.221

.314

.284

After

61,461

15,481

2394

639

693

6256

4956

.252

.321

.344

Initially, all I did was the research on the hitter data set out above. Since then, I've
learned that if you want to evaluate pitchers, you've got to do it from matched innings by
pitchers if possible. So I found the 41 pitchers who had at least 1/3 IP before 1945 and at
least 1/3 IP after 1945, and checked their matched innings before and after 1945. I came up
with 15,457.2 matched innings with the following results:

IP

H

HR

BB

K

Before

15,457.2

10,736

204

6910

6409

After

15,457.2

14,942

799

4840

4966

There are two factors we haven't addressed: parks and players ages. While I haven't
investigated it, I'd expect that each set of parks was about neutral for its own time frame.
However, the players in the "after" group are always older by a few years than their matched
at bats from "before". It is clear that aging alone cannot come close to accounting for
differences of this magnitude. It would be nice to try and filter out the effect of aging,
but I have yet to see any study of aging which would enable us to do so. That said, we must
realize that aging has some effect on the data in the studies.

One can derive conversion factors from these two sets of data (I'm using post 1945 as the
base), and I will do so for both the hitting and pitching data in categories common to each set
of data:

Batters

Pitchers

Hits

1.140

1.392

HR

2.415

3.910

BB

0.748

0.700

K

0.841

0.775

Interestingly, even though there was expansion in the number of teams after 1945, the effects
are more pronounced for the pitchers. Maybe the pitchers had already paid a heavy price for the
training methods and pitcher usage patterns of Japanese ball at the time, but I suspect it would
have to be both to be a reasonable explanation in and of itself as many of the pitchers studied had
limited pre-1945 use. In any event, both sets of data show hits up sharply, though nowhere near as
sharply as homers, which shot through the roof. Walks and strikeouts are both down a large amount.

I'd like to know more about pre-1945 ballparks, but I'd suspect the post-1945 ballparks did a
much better job of making the home run a part of the game. Balls may have been bouncier because
rubber was no longer being reserved for military use. Also, many young men who had been in the
service (or would have been had the war continued) were now available to play ball.

For a while, I puzzled over the way walks and strikeouts dropped in tandem given the rise in hits
and power hitting. My initial reaction was that hitters would have been swinging more freely,
which I would expect would eliminate the likelihood of a drop in the strikeout rate. I was a little
surprised pitchers didn't walk more guys, as I thought they might well mimic the reaction of the
majors in the 1920's and work more carefully to hitters, thus raising walk rates. It seems like the
Japanese either by plan or accident realized the truth that if you walked someone and he was batted
in via an extra base hit, he scored. That means it's even more important to limit how many
free passes you issue when power is a greater part of the game. One conclusion I make from this
data is that before 1945, Japanese hitters more consistently worked pitchers deep into counts in
hopes of drawing a walk, but at the price of striking out more often. When hitting and power rose
so sharply after 1945, there was a lesser emphasis on just waiting for a walk and more on trying to
get a hit, it would seem.

Just looking at the hitters' data, the same hitters with the same number of at bats had
14% more hits after 1945, with a little over one-half of the increase in hits coming in the
various extra base categories. On base percentage rose only about 2%, however, because after
1945 walk totals down so much. Slugging percentage rose 21%, largely due to the rise in extra
base hits.

I'll leave further interpretation of the data to others at least for the time being.
However, the data seemed far too important to fail to report it.